Electrical wires are conventionally joined by stripping the ends of insulation, scraping them clean, twisting the ends together, and applying solder to electrically join the ends together. If inadequate heat or flux are applied, or the wires not properly cleaned, a high resistance or cold soldered joint results. To overcome these problems, wire nut solder-less connectors were introduced which comprise a plastic outer shell and an inner electrically conductive, tapered cylinder with a screw thread. To apply this connector, previously-stripped, bare ends of the wires are oriented in the same direction, twisted together and inserted into the wide end of the wire nut. Twisting the wire nut crimps the wires together as the tapered thread advances on the wires and cuts into them, electrically joining them.
Problems arise with use of wire nuts when heavy conductors or more than two conductors are to be joined. The joint becomes bulky. It is difficult to arrange for all of the conductors to be exposed to the screw thread. If all of the conductors are not joined, the joint may lower the voltage in the line and heat up to the point of causing a fire. Wire nuts remain quick and convenient splicing devices, but they would be greatly enhanced by including means to overcome the difficulties associated with their use on heavy and multiple conductors.